1. Field of the Invention
The present invention relates to an electrode for a living body, and more particularly, to an electrode which can transmit an electrical signal from a living body by using a simple electrode structure, and a biosignal measurement device using the electrode.
2. Description of Related Art
A living body is a kind of conductor and minute currents may occur in the living body. Accordingly, internal properties of the living body may be measured by sensing the minute currents from the living body and detecting a change of the minute currents with respect to an external stimulus. Generally, an electrocardiogram (ECG), an electromyogram (EMG), an electroencephalogram (EEG), a galvanic skin response (GSR), an eye electrooculogram (EOG), body temperature, pulse, blood pressure, body motion, etc. may be measured by using the above described principle. An electrode for a living body is used for sensing a change of a biosignal.
FIG. 1 is a perspective view illustrating a conventional electrode and biosignal measurement device, and FIG. 2 is a cross-sectional view illustrating an attachment state of the electrode of FIG. 1.
Referring to FIGS. 1 and 2, a conventional electrode 10 includes an adhesive sheet 20 and a metal electrode 30. The adhesive sheet 20 has insulating properties and is in the form of a round shape. The metal electrode 30 makes direct contact with a living body. Also, the metal electrode 30 is formed of a conductive material. The metal electrode 30 includes a contact portion 32 widely provided on the bottom surface of the adhesive sheet 20 and a protrusion 34 formed on the center of the contact portion 32. The protrusion 34 may be exposed to the outside of the adhesive sheet 20 via a hole. An adhesive material is formed on the bottom of the adhesive sheet 20. Accordingly, the electrode 10 may be closely attached onto the skin of a body.
A biosignal measurement device 1 includes a main controller 40, the electrode 10 and a cable 50. A socket 52 is provided at the end of the cable 52. A groove is formed in the socket 52 to be engaged with the protrusion 34. Accordingly, the socket 52 and the metal electrode 30 may be electrically connected to each other. The cable 50 may be connected to the electrode 10 via the socket 52. Also, the cable 50 may be connected to the main controller 40 via a plug provided opposite to the socket 52. When the electrode 10 is attached onto a living body, the main controller 40 may measure a biosignal. Also, the main controller 40 may measure an ECG, an EMG, an EEG, a GSR, an EOG, body temperature, etc. from the received biosignal.
Generally, the metal electrode 30 is directly exposed on the bottom of the electrode 10. While the adhesive sheet 20 is provided, a contact between the skin and the metal electrode 30 may not be stably maintained. Accordingly, a gel-typed electrolyte is spread over the skin. By using the gel-typed electrolyte as a medium, a relatively stabilized connection state may be maintained between the skin and the metal electrode 30.
However, although the gel-typed electrolyte is used, the connection using the conventional electrode may be easily affected by some factors that may interfere with a stable connection. As an example, while a biosignal is being transmitted from the skin through a process of skin-gel-metal electrode 30-socket 52-main controller 40, the biosignal may be weakened or noise may be introduced. Also, the metal electrode 30 and the socket 52 make point contact in the protrusion 34. Accordingly, an electrical connection state is very unstable. This can prevent an accurate measurement.
An electrode in the conventional art is made to be expendable and generally disposable, so a user uses a new electrode every time. Since frequent attachments and detachments between the socket and the electrode occur, unstable contact may often occur.
Also, a structure using the protrusion 34 and the socket 52 may be referred to as a snap connecting structure. The snap connecting structure is disadvantageous to miniaturize a biosignal measurement device. This is because the protrusion 34 is formed on the metal electrode 30 and thus, the electrode 10 may not be flattened. Also, since the socket 52 for electric connection occupies a considerable area for installation, the protrusions 34 of the electrode 30 should be separated at the minimal interval needed for installation of the socket 52, such that the electrode 30 may not be reduced.
Also, when integrating a plurality of electrodes onto a single body, a plurality of corresponding protrusions or snaps is required. Accordingly, the electrode or the device may not be easily miniaturized.
Also, when providing a plurality of snaps on a single body, an interval between each snap needs to be identical to an interval between sockets to be properly connected with the snaps. When the interval between the snaps is smaller than the interval between the sockets, the sockets may not be installed on an electrode. Also, when the interval between the snaps is larger than the interval between the terminals, connecting the sockets and snaps may cause the electrode to become deformed.
Accordingly, an electrode in a simple structure ensuring a stable connection, and that can also be easily miniaturized, is required.